In the example of commercial beer production it is typically necessary to reduce the relative concentrations of haze forming compounds in order to prevent the non-microbiological or colloidal “haze” which results from the formation of macroscopic molecular assemblies of polyphenol (sometimes called tannin) compounds and polypeptides. Such colloidal haze formation can affect the drinking experience, is unattractive to consumers (who associate it with microbiological haze) and limits the commercial storage life of beer. Haze forming compounds are often removed by bulk addition of “fining agents” such as hydrophilic silica hydrogel (silica) which binds interacting polypeptides and polyvinylpolypyrrolidone (PVPP) and similar products (such as the commercial agent Polyclar AT) which bind polyphenols. These agents are mixed with the beer and then removed from it by decanting/filtration or similar processes. Similar haze reducing methods and procedures have been known and used for hundreds of years.
The literature on treatment of beer to reduce haze formation offers little consensus on exact mechanisms responsible for haze formation (1, 2). In truth, the relative importance of different mechanisms may vary from beer to beer, brewery to brewery, and with different conditions such as storage temperature. However it does appear that haze is formed via micro and then macroscopic assembly formation based on interaction of proteins and polyphenols. Some (e. g., proline-rich) proteins and some (e. g. dimeric favan-3-ol) polyphenols may be more prone to haze formation than other proteins and phenols. Significant haze formation appears to be somewhat of a time-dependent and thus stochastic process. As such its reduction to consumer desired levels can be obtained by various routes including reducing general concentrations of the proteins or polyphenols, or both proteins and polyphenols involved in haze formation. Naturally what is more to be desired is reduction of the specific protein, polyphenol, or both protein and polyphenol compounds which are more prone to produce haze formation (1, 2). That outcome is desired as it results in less reduction in natural beverage constituents.
U.S. Pat. No. 6,001,406 describes a method for stabilizing a beverage containing haze causing substances. This patent relates to a method for the simultaneous removal of polyphenols and proteins from a beverage by contacting the beverage with an ion exchanger that is capable of adsorbing both types of substances. The characteristic feature of the ion exchanger to be used is that it is a water insoluble porous hydrophilic matrix to which ion exchanging groups are covalently bound. Preferably, Q SEPHAROSE™ Big Beads (QBB) from GE Healthcare Bio-Sciences AB are used to remove colloidal haze precursors. The goal of the process is only to remove enough precursors to eliminate significant haze formation; not to remove all the haze promoting precursors as they may also confer head-foam formation, flavour tones and other favourable properties on the beer. The QBB-based system may offer several advantages over use of fining agents including increased beer storage life, elimination of the (perceived non-ecologically friendly) need to add and then discard additives, elimination of concerns related to possible inability to recover all added substances, plus use of more biocompatible and natural materials (e. g., agarose versus PVPP). The limitations with this technique are the cost of the Q-ligand modified agarose BB, that Q-modified media may show greater tendency to irreversibly adsorb protein and other beer constituents (i. e. foul) than for example media which does not contain charged ligands, the cost of chemical and other agents for cleaning in place (CIP) and that the QBB bed must be changed when or if it becomes fouled to a degree not amenable to CIP treatment.